7.2 C57.13 Instrument Transformers – J. Smith – Unapproved Minutes

Chair’s Remarks & Announcements

The Instrument Transformer Subcommittee met on Wed Oct 8 at 10:30 AM

6 members and 7 guests attended. The meeting was chaired by R. McTaggart

The previous meeting’s minutes were approved as written and there were no Patent issues.

7.2.1 Working Group Reports

7.2.1.1 Working Group on Test Requirements for High Voltage Instruments Transformers Rated 115 kV and above

The WG met on October 7, 2008. Six (6) members and thirteen guests attended the meeting. The meeting was co-chaired by Mr. P. Riffon and Mr. Ross McTaggart.

The agenda has been reviewed and accepted as written.

Minutes of Charlotte meeting were approved as written.

The IEEE patent disclosure requirement policy was discussed. None of the members and guests present during the meeting were aware of any patents related to the work of the WG.

The first technical subject on the agenda was the discussion on Mr. Rolando Gomez's comments regarding dissolved gas content values. Since Mr. Gomez was not able to attend the meeting, the discussion has been postponed for a second time to the next meeting in Miami.

Comments received on the survey made within the WG and the Instrument Transformer Subcommittee on Draft 3 of C57.13.5 have been discussed and the following has been agreed upon:

-Three full impulses will be kept for the routine impulse test procedure but additional waveshapes comparison among the three full impulses will be required in case where the comparison with the reduced impulse shows small differences or when this comparison is not available in case of multiple identical units to be tested for which the application of a reduced impulse wave may be waived.

-Nominal and maximum system voltage values will be changed to usual IEEE nominal and maximum system voltage values. Actual edition of C57.1.3.5 is using IEC system voltage values.

-External RIV values came from former NEMA values. Values will be kept as they are for the next edition.

-References to pressurized electrical equipment enclosures will be moved to a new Bibliography section. There is no specific US standards concerning pressurized enclosures for electrical equipment. Applicable CENELEC "EN" standards will be added as additional informative documentation about pressure vessels used in electrical equipment not containing corrosive gas such as oxygen and/or water.

-Maximum permissible initial level for acetylene (0,5 p.p.m.) will be kept as stated in the first edition since some residual acetylene may be seen in oil even after oil treatment.

Since no negative ballots have been received during the survey made on D3, D4 will be prepared and will take in consideration the decisions made during the meeting. D4 will then be sent to IEEE for an official ballot.

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7.2.1.2 PAR P1601 Optical Current and Voltage Sensing Systems - F. Rahmatian (TC/ITSC) and H. Gilleland (PSIM)

This WG did not meet in Porto

7.2.3 Old Business

7.2.3.1 C57.13 Revision

A number of the members comments were reviewed before running out of time. The key points were that the accuracy classes should include those in C57.13.6 and that there should be 4 test points. It was proposed that the 1.2 and possibly 0.6 class should be eliminated. It was also noted that there are no protection classes for VT’s. Vladimir Khalin volunteered to rewrite 8.1.10 (Calculation of current transformer ratio by the algebraic method) and to revise 8.9 (Measurement of open-circuit voltage of current transformers) by the next meeting. There was disagreement about whether the C57.13.5 test values should be put into the next revision. Some felt that the customer should have the choice of specifying C57.13 with less stringent testing or C57.13.5 with more stringent testing. This issue needs to be resolved before we go much further.

7.2.4 New Business

Partial Discharge Testing

The following points were discussed:

•C57.13 has very low requirements & little detail

•C57.13.5 has requirements similar to IEC but no test ckts or detailed methods

•IEEE C57.113 presently applies to Transformers & Shunt Reactors only

•Any PD Standard developed or referenced should apply to CT’s, VT’s & Combined Metering Units – either general or specifically covering all

•Agreed that test levels should remain in Product std (C57.13 & 13.5)

•Options are: 1) separate document

2) expand scope of C57.113

3) Include in C57.13

•Proposal for TF to study & determine best approach – accepted by the attendees

•Thang Hochanh will chair TF under SC Dielectric Tests

•Lorin Wagenaar will arrange for a time slot which does not interfere with other Instrument Transformer meetings

7.2.5Adjournment

The meeting was adjourned at 11:55 AM